Brunellia gracilis C.I.Orozco, 2020

Orozco, Clara Inés, Pérez, Álvaro J., Romoleroux, Katya, Bohórquezosorio, Andrés Felipe & Aldana, José Murillo, 2020, Three new species of the Andean genus Brunellia (Brunelliaceae) from Colombia and Ecuador, Phytotaxa 433 (1), pp. 27-40 : 31-34

2. Brunellia gracilis C.I.Orozco , sp. nov. ( Figs. 4 , 5, 6 , 7 ).

Type:― COLOMBIA. Cauca: Municipio del Puracé, Parque Nacional del Puracé, camino hacia la cascada, San Nicolás frente a la cabaña San Nicolás, 2600–2800 m, 12 October 1992, C. I. Orozco & C. Mayorga 2582 (holotype: COL! –two sheets, flowers and fruits).

Diagnosis:― Brunellia gracilis differs from the closely related species B. bullata Cuatrecasas (1970: 114) and B. cayambensis Cuatrecasas (1970: 115) by its more slender habit and the more narrow tree crown with fewer branches, by the thick leaf primordia with two interpetiolar stipules vs. thin leaf primordia with usually 4 interpetiolar stipules, by the abaxial leaflet surface with dense, permanent and ochroleucous indument vs. glaucous, or with light-yellow indument, by the smooth adaxial surface of the leaflets vs. strongly to softly bullate, by the leaf margin thickened, not revolute and usually entire vs. thin, serrate and revolute, by the irregular growth of the petiole, and by the tendency to develop a lower number of sepals (4 to 5, vs. 5 to 6) (see also Table 2).

Description:― Tree, 4–6 m tall, with a narrow crown. Stem and branches slender, terete or subterete, scarcely furrowed toward the top, with a dense and smooth dull yellow indument, with trichomes patent, internodes (1.7–) 2.2– 4.4 cm long, the nodes slightly thickened. Stipules geminate, conical, less than 1 mm long. Leaves opposite, (5.2–)6.7–14(–34) cm long, petiolate, usually imparipinnate, with (1)3–9(11) leaflets, interjuga 1.5–2.7 cm long; petiole with dark-yellow indumentum (in dry material), (0.1–)2.1–3.3(–6.5) cm long, terete, of variable size at the same node. Leaflets stipelated, subtended by a short petiolule, the stipels 2 on the rachis, subulate, 1–2 mm long, densely pilose; petiolule thickened, (2–)3–5(–6) mm long, the terminal one 6–17 mm long; blade oblong-elliptic, (3)5–12 × (1.6–) 2–5 cm, coriaceous. The adaxial surface usually flat, dark green, and shiny in fresh material, black in young leaves, the oldest yellowish green in dry material, glabrous; the abaxial surface always covered by straight and loose trichomes, ochroleucous (ochraceous in dried material). Base usually obtuse, somewhat unequal; apex acute, mucronate, up to 1 mm long; margin thickened, entire; secondary veins in (10)13–19 pairs, diverging at a 50° angle, ascending, impressed on the adaxial side, of slightly raised on the abaxial side, the midvein more prominent than the secondary veins, the leaf reticulum usually inconspicuous by the indument. Inflorescence axillary, thyrsoid, lax, (2.4–)4–9 × (2–) 5–7.3 cm, bracteate, pedunculate, covered by ochraceous indument, with a conspicuous terminal flower at the end of each inflorescence branch, the paracladia with acrotonic proliferation; flowered part of inflorescence 40–50% of total length. Bracts lanceolate, sometimes divided, 1.3–2.0 × 0.1–0.8 mm; peduncle of the inflorescence terete in fresh material, smoothly furrowed when dried, (2–)3–5.6 × 0.2–0.4 cm. Flowers actinomorphic or zygomorphic, hermaphroditic, pedicellate, bracteolate. Pedicels terete, 1–2.5 mm long, the terminal one up to 2.5–6(–7) mm; bracteoles 2 per flower, linear, 1.7–2.7 × ca. 1 mm, pilose. Buds ovoid, 2–2.7 mm in diameter. Calyx usually with 4(5) sepals, with one of them sometimes divided in half, 5–6 mm in diameter, the sepals oblong to elliptic, 1–2 × 1–2 mm, thick, the apex usually thickened adaxially, densely hairy abaxially, adaxially with long and short trichomes, some of which are curled at the apex; corolla absent. Stamens 8–10, 2–2.5 mm long, filaments 1–1.5 mm long, anthers globose, 1 mm in diameter. Ovary with 4–5 carpels, inserted on a bristly disk. Fruit consisting of (2)5 follicles, ovoid, 5–7 × 4–5 mm, with bristly trichomes, the pedicel 4–8 mm long; calyx in fruit 7–8 mm in diameter, endocarp urceolate, 3–4 × 3–4 mm; seed 1, ovoid, ca. 3 × 2 mm, red, glossy, flattened.

Etymology:—The specific name refers to the slender habitus of the tree.

Habitat and distribution:— Brunellia gracilis is only known from southwestern Colombia, in the Andean region of the Central Cordillera, Macizo Colombiano, in Cauca and Huila departments, between 2600–3400 m a.s.l. At the highest elevations, B. gracilis is sympatric with B. pitayensis Cuatrecasas (1985: 89) , probably a synonym of B. almagarensis Cuatrecasas (1970: 156) .

Phenology: Flowering and fruiting take place in March, June, October and November.

Conservation status:—Most of the collections are from Puracé National Park, which belongs to the System of Protected areas, indicating that populations of this species are preserved. This species was also found outside of the park, in Inza, Paez and towards the Plata in Huila department ( Fig. 5). A large population was also recently found in Cauca, Municipality of Paez, near Mosoco, in patches of forest along the road, outside the National Park limits. Recent observations made on specimens at CAUP document that this species was collected in the Puracé National Park until to 2006. Fragmentation of the forest was observed in part of the distribution of the species (Mosoco). This species is proposed as Vulnerable (VU), under the criteria B2, because the area of occupancy is less than 2000 Km 2 (647 Km 2, calculated by the minimum convex polygon method: IUCN 2013) ( Fig. 5).

Observations:—According to the taxonomic treatment by Cuatrecasas (1970, 1985), B. gracilis can be included in the sect. Brunellia subsect. Bullatae Cuatrecasas (1970: 113) , mainly by the number of secondary nerves, ovoid shaped endocarp, urceolate when dry. In this subsection, they were originally included two species, i.e. Brunellia bullata Cuatrecasas (1941: 341) from Colombia and Brunellia cayambensis Cuatrecasas (1970: 115) from Ecuador. Both species also share the inflorescence morphology with B. gracilis ( Orozco & Weberling 1999) . However, on the contrary of B. gracilis , both B. cayambensis and B. bullata are sturdy trees, with a broad and densely branched crown, and evident thickened nodes ( Figs. 7 ). Additional differences are reported in Table 2 ( Figs. 4 , 6 , 7 ).

The small subsect. Bullatae, with moderate to high support, is positioned in a large clade, including taxa from different sections (i.e., sect. Brunellia and sect Simplicifolia ) (Murillo et al. in preparation). However, this small subclade including B. gracilis is closely related to the subclade of species with simple leaves, larger fruits and boatshaped endocarp. This latter subclade includes the sympatric Brunellia pitayensis .

Additional specimens examined:― COLOMBIA. Cauca: Municipio La Cruz, volcán Doña Juana, Reserva Santa Helena , 3270 m, 8 March 2004, D. M. Munar et al. 481 (CAUP! –buds) ; Municipio de Inza, vereda Rio Sucio, Los Alpes , 3400 m, 2°28’34.2’’N 76°13’6.8’’W, 19 November 1998, O. Rivera et al. 815 (COL! –buds) ; Municipio de Paez, vereda Escalareta, hacia el Resguardo indígena Mosoco , bajando del Páramo de Pizno , 3382 m, 2°42’42.5”N 76°12’76”W, 24 June 2017, C. I. Orozco et al. 4148 (COL! –buds) ; 3361 m, 2°42’47.5’’N 76°12’22.13’’W, 24 June 2017, C. I. Orozco et al. 4149 (COL! flowers and fruits); 3340 m, 2°42’54’’N, 76°12’18.1’’W, 24 June 2017, C. I. Orozco et al. 4150 ( COL!) ; Municipio Puracé, Parque Nacional del Puracé , termales de San Juan, 3245 m, 3 July 2006, S.P. Acosta & B. R. Ramírez 039 (CAUP! –flowers and fruits) ; 3120 m, 15 February 2000, B. R. Ramírez 12829 (CAUP); 3200 m, 12 June 1991, B. R. Ramírez, 3759 (COL! –fruiting; CAUP! –fruiting) ; Coconuco, Corregimiento de Paletará, camino hacia la laguna del Buey , 2900–3020 m, 16 October 1992, C. I. Orozco & C. Mayorga 2677 (COL! –flowers and fruits) ; C. I. Orozco & C.Mayorga 2577 (COL! –fruits); 140 km of La Plata road, 3150 m, 2°19’00’’N 76°17’00’’W, 25 March 1986, B. A. Stein 3576 (COL! MO! –flowers and fruits) ; Ibidem , 4 October 1984, G. Lozano et al. 4504 (COL! –buds) ; Municipio de Totoró, 32 Km Este de Totoró , 3050 m, 2°33’00”N 76°09’00”W, May 1984, J. L. Luteyn et al. 10169 (COL!; NY! –fruiting) .

Figures

FIGURE 4. Brunellia gracilis. A. Flowering and fruiting branch. B. Indument of abaxial leaflet. C. Details of leaves and stipules in early development. D. Branching of the inflorescence. E. Floral buds in details at the end of the inflorescence. F. Single floral bud G. Sepals adaxially thickened at the apex. H. Hermaphrodite flower. I. Mature follicles. J. Fruit opening along ventral suture, with the seed attached to the endocarp through the funiculus. Drawing by Marcela Morales.

FIGURE 6. Brunellia gracilis. A. Habitat. B. Tree habit. C. Uneven growth in length of the vegetative branches. D. Abaxial surface of the leaflets, reticulation and margin. E. Foliar buds and stipules. F. Flowering branches, apex of the leaflets mucronate. G. Infructescence, bristly hairs on the follicles. H. Branching of the inflorescences, floral buds pilose. (Photographs by C. I. Orozco).

FIGURE 7. Brunellia bullata (A–G), Brunellia cayambensis (H–L).A. Tree habit. B. Leaflets bullate. C. Stem ancipital, nodes thickened, and stipules insertion scars. D. Abaxial surface of the leaflets with scarcely light yellowish trichomes, margin 1- to 2-serrate. E. Young leaves folded by their central nerve. F. Buds glabrous. G. Inflorescences and infructescences congested. H. Tree habit. I. Vegetative growth of the leaves and stipules. J. Bullate surface of the leaflets, leaflets folded by their main nerve. K. Abaxial surface of the leaflets glaucous. L. The glabrous immature infructescence, with the striate peduncle. (Photographs by C. I. Orozco).